Method of fire protection using recirculation of combustion products

ABSTRACT

A method for fire protection wherein a nozzle discharges an extinguishant in response to a predetermined fire condition in a manner to create an aspiration effect which circulates the combustion products from the fire in a path including the fire. The circulation of the combustion products is terminated and the rate and manner of discharge of extinguishant from the nozzles can be changed in response to an additional predetermined fire condition.

3a780a8ll United States Patent [191 Yeo X [451 Dec.25,1973

METHOD OF FIRE PROTECTION USING RECIRCULATION OF COMBUSTION PRODUCTSInventor: Cheng Yao, Weston, Mass.

[73] Assignee: Factory Mutual Research Corporation, Norwood, Mass.

[22] Filed: Aug. 3, 1972 [211 Appl. Noi: 277,495

Related US. Application Data [62] Division of Ser. No. 198,386, Nov. 12,1971, Pat. No.

[52] US. Cl. 169/12, 169/1 A [51] Int. Cl. A62c 35/00 [58] Field ofSearch 169/1 A, 5-18 [56] References Cited UNITED STATES PATENTS2,498,512 2/1950 Thompson 169/12 l2 b I 6 3,463,234 8/1969 Van Baak169/12 X Primary Examiner--M. Henson Wood, Jr. Assistant Examiner-JohnJ. Love Attorney-JosephM. Lane et a].

57 ABSTRACT A method for fire protection wherein a nozzle dis- I chargesan extinguishant in response to a predetermined fire condition in amanner to create an aspirav tion effect which circulates the combustionproducts from the fire in a path including the fire. The circulation ofthe combustion products is terminated and the rate and manner ofdischarge of extinguishant from the nozzles can be changed in responseto an additional predetermined fire condition.

l0 Claims, 3 Drawing Figures METHOD OF FIRE PROTECTION USINGRECIRCULATION OF COMBUSTION PRODUCTS This application is a division ofapplication Ser. No. 198,386, filed Nov. 12, 1971, now U.S. Pat. No.

CROSS REFERENCE TO RELATED APPLICATION This application relates to U.S.Pat. application Ser. No. 131,988, now U.S. Pat. No. 3,692,118, filed onApr- 7, 1971, by the same inventor as the present invention and assignedto the same assignee as the present invention. The disclosure of thelatter application is hereby incorporated by reference.

BACKGROUND OF THE INVENTION This invention relates to a method for fireprotection, and more particularly to such a method which utilizes theproducts of combustion from a fire to aid in extinguishing the fire. Themethod includes a discharge device and method for achieving the above.

In the above-mentioned related application Ser. No.

Towards the fulfillment of these and other objects of the presentinvention, the method'of the present invention BRIEF DESCRIPTION OF THEDRAWINGS Comprises the steps of discharging extinguishant towards afire, circulating the combustion products from the fire in a pathincluding the fire and terminating the circulation of combustionproducts while maintaining the extinguishant discharge.

, 2-2 of FIG. I; and

131,988, a fixed fire extinguishing system is disclosed in which thecombustion products of a fire developing in the enclosure to beprotected are circulated back towards the fire at the early stage of thefire development to prevent the ingress of air to the fire. Thecirculation of the combustion products is achieved by the use of aplurality of aspiration-type nozzles which are mounted near the ceilingof the enclosure, with each having an inlet opening for receiving theproducts of combustion and a discharge opening for discharging theproducts of combustion. When actuated, the nozzles discharge anextinguishant towards the fire which creates an aspiration effect andcirculates the products of combustion in a path upwardly from the fire,

through the nozzles, and downwardly into the fire. In this manner, airentering the building through its windows and doors and passing towardsthe fire is blocked by the barrier created by the products ofcombustion.

Although the above arrangement was found to be effective inextinguishing fires, it suffered from the fact that the extinguishantdischarge velocity from the nozles had to be set at a relatively highvalue in order to obtain the aspiration effect. Since this wasaccomplished by utilizing a relatively small discharge opening, theextinguishant discharge from the nozzles was ineffective in directlyfighting the fire, since it was unable to penetrate the fire plume.This, of course, imposed limitations on the fire-fighting capability ofthe system, especially in fire situations in which the recirculation ofthe combustion products around the fire could not achieve total fireextinction. I

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide a method of the above type in which the combustionproducts from the fire are circulated in a path.

including said fire, with the circulation being termi nated locally inresponse to additional information received from the fire.

It is a further object of the present invention to provide a method forfighting a fire in which the rate and manner of discharge from thenozzles is altered upon the termination of the circulation of thecombustion products.

FIG. 3 is a view similar to FIG. 1, but showing the device of thepresent invention after responding to a fire condition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The discharge device utilizedin the method of the present invention is depicted in FIG. 1 of thedrawings, and includes a nozzle unit 10 defining a discharge outlet lGaat its lower end as viewed in FIG. 1 and having a T-shaped couplingmember 12 threadably connected to its upper end. One end portion of thecoupling member 12 is internally threaded as shown at 12a for connectionto a branch line 13 for supplying an extinguishant such as water, itbeing understood that a typical fire protection system will includeseveral discharge devices and branch lines, along with submains, risers.and a main, to supply the branch lines with an extinguishant, such aswater, in a conventional manner, and as shown and described in theabove-mentioned related application.

A closure plug 14 is threadably engaged in the other end portion 12b ofthe coupling member 12 and defines a central opening which receives avalve stem 16 slidably extending therethrough. A valve head 18 isconnected to one end of the valve stem 16 and is adapted to engage acooperating seat 20 supported by the internal wall of the couplingmember 12 to block the flow" of extinguishant through the couplingmember.

A lever arm 22 is pivotally mounted to the plug 1 4 V and is adapted tobe connected, by means of a fusible link 24, to a lever arm 26 fixedwith respect to the plug. The pivotal lever arm 22 has aprojectionengaging the other end of thevalve stem 16 to maintain the valve head 18against the seat 20 as long as the fusible link 24 maintains theconnection between the levers 22 and A circumferential groove 34 isformed in the outer periphery of the nozzle unit 10 for reasons thatwill be explained in detail later.

An open-ended, hollow housing 40, formed in the shape of a venturi,extends over the bottom portion of the nozzle unit 10 and has an inlet40a and an outlet 40b for respectively receiving and discharging theproducts of combustion from the fire. An extension 42 for the dischargeopening 100 is mounted relative to the housing 40 by means ofa pluralityof struts 44, two ofwhich are shown in FIG. 1. The extension 42 extendsover the discharge end portion of the nozzle unit 10 and has a dischargeopening 420 which registers with the discharge outlet a, with theopening 42a being of a smaller diameter than the outlet-10a. In anexemplary embodiment of the present invention, the outlet 10a would havea diameter of approximately one-half inch and would discharge theextinguishant at a spray angle of approximately l50 degrees, while theopening 42a would have a diameter of approximately one-eighth of an inchand would discharge the extinguishant at a spray angle of approximatelyl00 degrees.

The housing 40 is connected relative to the nozzle unit 10 by means ofthree substantially L-shaped con-' necting arms 50. Each of the arms 50consists of a lower portion 500 which engages underneath aninwardly-directed circular flange 400 formed on the upper end of thehousing 40, and an upper portion 50b which engages a split ring 52extending around the upper end portion of the nozzle unit 10 and havingits ends normally connected by a fusible link 54. The elbow portions ofthe arms 50 are supported by, and extend within, the circumferentialgroove 34.

Referring specifically to FIGS. 1 and 2 for a better view of theinterconnection between the upper arm portions 50b and the ring 52, itis seen that the arm portions are curved slightly at their upper ends sothat they extend around, and over, the top surface of the ring. In thismanner the ring 52 can be designed to maintain the arms 50 under aslight, inwardly-directed spring tension in order to maintain the arms,and therefore the housing 40, in the position shown in FIG. 1. Ofcourse, when the link 54 fuses in response to a predeterminedtemperature, the ends of the ring are free to separate, which willrelease the arms 50 and therefore permit the housing 40 to fall from thenozzle 10 under the force of gravity.

The temperatures required to fuse the fusible link 24 and the fusiblelink 54 may vary in accordance with particular design considerations. Apreferred embodiment would have the fusible link 54 adapted to fuse at atemperature greater than the fusible link 24, with a specific example ofthe fusing temperatures being 165F. for the link 24 and 500F. for thelink 54.

As an example of the method of the present invention and using water asan example of the extinguishant, upon the temperature in the vicinity ofthe fusible link by the extension 42. This relatively high velocity issufficient to induce the products of combustion from the fire to enterthe housing 40 through its inlet 40d. This, plus the venturi shape ofthe housing 40, createsan aspiration effect which circulates theproducts of combustion from the fire in a path from the-fire, downwardlythrough the inlet 40a, and outwardly from the housing through the outlet40b. In this action the water is atomized into a fog, a large portion ofwhich circulates with the combustion products in the above manner. Asemphasized, in the above-cited application, this circulation of thecombustion products creates a barrier which prevents air entering thebuilding through doors, windows, etc., from passing directly into thefire. As a result, the fire will be smothered and rendered relativelyeasy to extinguish.

In the event the above circulation of combustion products does notcompletely extingui the fire, and assuming the fire causes the tempe nevicinity of the device to increase to approximately 500F., the fusiblelink 54 will collapse, permitting a release of the. split ends of thering 52 and a release ,of the arms from the ring. The housing 40 willthus be released from the position shown in FIG. 1 and will fall awayfrom the nozzle unit 10. As a result, the device will take theoperational position shown in FIG. 3, with the extinguishant flowingdirectly into the nozzle unit 10 and being directly discharged from therelatively large outlet 100 at a relatively high rate and wide sprayangle. Thus, in the latter operational mode of the device, theabove-mentioned aspiration effect will be eliminated and the rate ofextinguishant discharge and the area of coverage will be increased.

Of course, in a system incorporating several of the discharge devices,it is apparent that, in a typical highchallenge fire situation, thedischarge devices directly over the fire may attain their directdischarge mode while the peripheral devices will circulate thecombustion products in the above manner. As a result the former deviceswill have a relatively good chance of extinguishing the fire directlysince the latter devices will prevent the ingress of air to the fire. Asa result. optimum fire fighting capability is achieved.

It is understood that the invention is not limited to the use of wateras an extinguishant, but can incorporate other extinguishants that lendthemselves to the above operation. For example, a water based foamforming fluid may be used in accordance with the fore- 24 reachinglF.,the link will collapse and permit a i pivoting of the arm 22relative to the arm 26 under the force of the valve stem 16 as a resultof the water pressure acting against the valve head 18. This permits the.and a relatively narrow spray angle due to the presence of therelatigiy srnall discharge opening 420 provided going. An example of thelatter would be a mixture of water and a foaming compound such as anyone of a number of synthetic surface active agents that are stable withthe fire products of combustion. The foaming compound could be injectedinto the waterline in re-- sponse to a fire situation and the resultingfluid, when discharged through the outlet 42a in accordance with theforegoing, would create the aspiration effect discussed above and inducethe products of combustion into the housing 40. The resulting mixture ofthe solution and the combustion products would cause the foamingcompound to foam, with the compound preferably being such that theresulting foam would consist of between 200-1000 parts combustionvproducts to 1 part of water by volume. Of course, upon the fusing of thelinks 54 and the resulting release of the housing 40 and discharge ofthe fluid from the larger outlet 10a. the fluid would remain it itsfluid state and would discharge directly to the fire in a spray ofdroplets with the said space greater than said predeterminedtemperature.

3. The method of claim 1 further comprising the steps of forming a foamin response-to said step of cirvided to each nozzle after apredetermined time delay,

can be incorporated in the system of the present invention. Also, thesizes of the outlet 10a and the opening 42a, as well as the fusingtemperatures for the links 24 and 54, may be varied in accordance withthe present invention.

Still other variations of the specific construction and arrangement ofthe method disclosed above can be made by those skilled in the artwithout departing from the invention as defined in the appended claims.

1. A method of fighting a fire comprising the steps of dischargingextinguishant towards said fire, circulating the combustion productsfrom said fire in a path including the fire, and terminating saidcirculation of combustion products while maintaining said extinguishantdischarge.

2. The method of claim 1 wherein said steps of discharging andcirculating are done in response to a predetermined temperature in thespace to be protected from fire, and wherein said steps of terminatingand maintaining are done in response to a temperature in lating anddischarging said culating and discharging said foam towards said fire.

4. The method of claim 3 wherein said extinguishant is a foam formingfluid, wherein said step of circulating causes the foaming of saidfluid, and wherein the discharge of said fluid is increased in responseto said step of terminating. 1

5. The method of claim 1 wherein said extinguishant is water, whereinsaid step of circulating causes said water to atomize, and wherein thedischarge of said water is increased in response to said step ofterminating.

6. The method of claim 1 further comprising the step of changing thespray angle of said discharge.

7. The method of claim 1 further comprising the step of changing therate of extinguishant discharge.

8. A method of fighting a fire comprising the steps of circulating thecombustion products from said fire in a path including said fire inresponse to a predetermined temperature existing in the space to beprotected, and terminating said circulation of combustion products inresponse to a temperature existing in said space greater than saidpredetermined temperature.

9. The method of claim 8 further comprising the steps of forming a foamin response to said step of cir-- culating and discharging said foamtowards said fire.

10. The method of claim 8 further comprising the steps of forming a fogin response to said step of circufog towards said fire. 8 t

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 r 1 Dt d December 25 1973 Inventor (s) Chang Yao It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 2, lines 'l-ll, cancel and rewrite as follows:

-Towards the fulfillment of these and other objects of the presentinvention, the method of the present invention comprises the steps ofdischarging 'extinguishant towards a fire, circulating the combustionproducts from the fire in a path including the fire and terminating thecirculation of combustion products while maintaining the extinguishantdischarge.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to theaccompanying drawings-- Column 2, lineIZ, cancel "ings" Signed andsealed this 30th day of April l97l4..'

(SEAL) Attest:

EDWARD HELETCHEPLJR. ,C. I LARSHALL 'DAH'Z-I Attestin-g OfficerCommissioner of Patents

1. A method of fighting a fire comprising the steps of dischargingextinguishant towards said fire, circulating the combustion productsfrom said fire in a path including the fire, and terminating saidcirculation of combustion products while maintaining said extinguishantdischarge.
 2. The method of claim 1 wherein said steps of dischargingand circulating are done in response to a predetermined temperature inthe space to be protected from fire, and wherein said steps ofterminating and maintaining are done in response tO a temperature insaid space greater than said predetermined temperature.
 3. The method ofclaim 1 further comprising the steps of forming a foam in response tosaid step of circulating and discharging said foam towards said fire. 4.The method of claim 3 wherein said extinguishant is a foam formingfluid, wherein said step of circulating causes the foaming of saidfluid, and wherein the discharge of said fluid is increased in responseto said step of terminating.
 5. The method of claim 1 wherein saidextinguishant is water, wherein said step of circulating causes saidwater to atomize, and wherein the discharge of said water is increasedin response to said step of terminating.
 6. The method of claim 1further comprising the step of changing the spray angle of saiddischarge.
 7. The method of claim 1 further comprising the step ofchanging the rate of extinguishant discharge.
 8. A method of fighting afire comprising the steps of circulating the combustion products fromsaid fire in a path including said fire in response to a predeterminedtemperature existing in the space to be protected, and terminating saidcirculation of combustion products in response to a temperature existingin said space greater than said predetermined temperature.
 9. The methodof claim 8 further comprising the steps of forming a foam in response tosaid step of circulating and discharging said foam towards said fire.10. The method of claim 8 further comprising the steps of forming a fogin response to said step of circulating and discharging said fog towardssaid fire.